Stencil sheets



United States Patent STENCIL SHEETS Shinjiro Horii, Chiyoda-ku, Tokyo, Japan N0 Drawing. Application September 9, 1952, Serial No. 308,700

l Claims priority, application Japan July 30, 1952 4 Claims. (Cl. 1173S.5)

This invention relates to the production of a stencil sheet for use in duplicating manuscript and typewritten documents, drawings and the like, and more particularly to the manufacture of a new composition with which a porous support such as Yoshino paper is coated or impregnated. Broadly the object of the invention is to utilize the film forming properties of the derivatives of polysaccharides modified in a new and novel manner.

The stencil sheets of the present invention have long keeping qualities and may be made and kept in a preferred condition for ready use without previous treatment. They are neither sticky nor tacky and they may be relied upon to cut easily and sharply with uniform visibility when written upon the stencil sheets, and produce an inklike impression on the backing sheets which may be read.

The prior art shows the use of various polysaccharide esters as the cementitious material in the making of the dry type of stencil sheets. These cementitious esters are usually the nitro derivatives of cellulose, or the acetic derivatives of cellulose, starch and various vegetable gums. Moreover, the effective modifying agents are usually added to the above composition. They are vegetable oils, fats and fatty acids. The oils, fats and fatty acids tend to oxidize after a time.

It is well known that acids greatly affect the stability of the nitro-cellulose, causing disintegration and rendering the sheet sticky, tacky and unfit for use in a comparatively short time.

Therefore, use has also been made in practice of various stable modifying agents such as alkyl esters of fatty acids (such as ethyl oleate and butyl stearate), higher fatty alcohols (such as oleyl alcohol and cetyl alcohol), naphthenic acids glyceride, heavy mineral oils, and fats or waxes (such as Japan wax, Chinese insect wax and carnauba wax).

Generally, if sufficiently large quantities of these modifying agents are incorporated, the materials sweat out to the surface and make a stencil disagreeable and objectionable to handle.

I have found that the combined use of microcrystalline waxes with a suitable modifying agent overcomes these objections, and I have secured a stencil sheet which, after drying, has a dry surface film free from stickiness and which is strong and durable, and may be easily cut freely and sharply.

The microcrystalline waxes are the new products derived from a suitable petroleum fraction or the still residuum by the special solvent extraction process developed recently in the petroleum industry. The microcrystalline waxes are apparently amorphous, but they consist of crystals of extremely small or microscopic. Their constituents are solid hydrocarbons of molecular weight averaging higher than the ordinary paratfin waxes. As is known, microcrystalline waxes contain minute hydrocarbon crystals and include such hydrocarbons as the solid isoparaffins, the solid naphthalene hydrocarbons and the solid normal paraflin hydrocarbons. The waxes, in spite of the higher melting points, are moderately soft and adhesive and also they have'higher capacity of oil absorption; forming a more uniform mixture of the wax and fatty oils.

According to this invention, as above described, microcrystalline waxes are especially used in combination with other ingredients in the manufacture of stencil sheets. Effectively the coated film, after the evaporation of solvents remaining on the base material, is very hard, elastic and uniform, differing radically from that containing other waxes such as Japan wax or ordinary parafiin wax. Moreover, the stencil sheets have long keeping qualities without any defect of becoming sticky. These special effects are due to the above mentioned peculiar properties of the microcrystalline waxes.

In carrying out the invention, I employ a base of open, porous paper in sheets or in web. The porous base is coated or impregnated with a coating composition mainly consisting of one or more of film-forming polysaccharide derivatives, such as nitrocellulose, cellulose acetate, ethyl ether of cellulose, methyl ether of starch, in a suitable solvent, such as a mixture of ethyl alcohol, ether, acetone, butyl alcohol, ethyl acetate, butyl acetate, glycol monoethyl ether, benzol, toluol and petroleum benzine, compounding therewith a mixture of microcrystalline wax with a suitable modifying agent, comprising one or more of fatty oils, higher fatty alcohols (such as oleyl alcohol and cetyl alcohol), mineral lubricating oils, naphthenic acids glyceride, alkyl esters of fatty oils (such as ethyl oleate and butyl stearate), butyl phthalate, and cresyl phosphate. If necessary, some quantity of pigments or dyes may be incorporated in the above mixture.

By way of example, the proportion of the ingredients is as follows, all parts being by weight:

Nitro-cellulose 45 Microcrystalline wax 20 Castor oil 40 Naphthenic acids glyceride 20 Ethyl oleate 30 Butyl stearate 30 Ethyl alcohol 200 Ethyl acetate 205 Butyl alcohol 50 Butyl acetate 60 Benzol Toluol 150 What I claim is:

l. A stencil sheet of improved keeping qualities and free from stickiness, comprising a fibrous base impregmated with a film-forming polysaccharide derivative selected from the class consisting of cellulose esters, cellulose ethers and starch ethers, and modified with a microcrystalline petroleum wax and a vegetable oil softening agent, said microcrystalline petroleum wax comprising about 10% by weight of the impregnating ingredients.

2. A stencil sheet of improved keeping qualities and free from stickiness, comprising a fibrous base impregnated with a film-forming polysaccharide derivative selected from the class consisting of cellulose esters, cellulose ethers and starch ethers, and modified with a microcrystalline petroleum wax and at least one softening agent for the film-forming polysaccharide selected from the class consisting of higher fatty acid esters, higher fatty alcohols, naphthenic glycerides, phthalate esters and phosphate esters, said microcrystalline petroleum wax comprising about 10% by weight of the impregnating ingreclients.

3. A stencil sheet as in claim 2 wherein said polysaccharide derivative is nitrocellulose.

4. A stencil sheet as in claim 2 wherein said polysaccharide derivative is nitrocellulose in an amount of about 4 5 parts by weight, said softening agent contains References Cited in the file of this patent about 45 parts by weight of castor oil, about 20 parts by UNITED STATES PATENTS welght of naphthenlc acld glycendes, about 30 parts by 6 6 S .wcight of ethyl oleate and about 30 parts by weight of 3 2 38:? 5 5: i fi' O l1 yl 5 am e and sa1d rmcrocrystal me wax 1s about 2 5 1,829,750 Horii Nov- 1931 p g the cqamlg a q weight 2,142,039 Abrams Dec. 27, 1938 

1. A STENCIL SHEET OF IMPROVED KEEPING QUALITIES AND FREE FROM STICKINESS, COMPRISING A FIBROUS BASE IMPREGNATED WITH A FILM-FORMING POLYSACCHARIDE DERIVATIVE SELECTED FROM THE CLASS CONSISTING OF CELLULOSE ESTERS, CELLULOST ETHERS AND STARCH ETHERS, AND MODIFIED WITH A MICROCRYSTALLINE PETROLEUM WAX AND A VEGETABLE OIL SOFTENING AGENT, SAID MICROCRYSTALLINE PETROLEUM WAX COMPRISING ABOUT 10% BY WEIGHT OF THE IMPREGNATING INGREDIENTS. 